Well.....

Passive recreation= A field of green grass or any open public space concurrently used for another intermittent use/purpose (drainage detention, retention...) Passive most of the time....nice to look at....someone could come along and setup a frisbee golf, coquet or lawn dart game at any time.....
Active recreation= A playground, ball fields, indoor pool/recreation facility, any recreational area that includes significant infrastructure for the purposes of active sports or organized events.